[RFC 1/2] PCI/IOV: Introduce pci_iov_sysfs_link() function

[Niklas Schnelle]

currently pci_iov_add_virtfn() scans the SR-IOV bars, adds the VF to the
bus and also creates the sysfs links between the newly added VF and its
parent PF.

With pdev->no_vf_scan fencing off the entire pci_iov_add_virtfn() call
s390 as the sole pdev->no_vf_scan user thus ends up missing these sysfs
links which are required for example by QEMU/libvirt.
Instead of duplicating the code introduce a new pci_iov_sysfs_link()
function for establishing sysfs links.

Signed-off-by: Niklas Schnelle <schne...@linux.ibm.com>
---
 drivers/pci/iov.c   | 36 ++++++++++++++++++++++++------------
 include/linux/pci.h |  8 ++++++++
 2 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 4d1f392b05f9..d0ddf5f5484c 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -113,7 +113,6 @@ resource_size_t pci_iov_resource_size(struct pci_dev *dev, 
int resno)
 static void pci_read_vf_config_common(struct pci_dev *virtfn)
 {
        struct pci_dev *physfn = virtfn->physfn;
-
        /*
         * Some config registers are the same across all associated VFs.
         * Read them once from VF0 so we can skip reading them from the
@@ -133,12 +132,34 @@ static void pci_read_vf_config_common(struct pci_dev 
*virtfn)
                             &physfn->sriov->subsystem_device);
 }
 
+int pci_iov_sysfs_link(struct pci_dev *dev,
+               struct pci_dev *virtfn, int id)
+{
+       int rc;
+       char buf[VIRTFN_ID_LEN];
+
+       sprintf(buf, "virtfn%u", id);
+       rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
+       if (rc)
+               goto failed;
+       rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
+       if (rc)
+               goto failed1;
+
+       kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);
+
+       return 0;
+failed1:
+       sysfs_remove_link(&dev->dev.kobj, buf);
+failed:
+       return rc;
+}
+
 int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 {
        int i;
        int rc = -ENOMEM;
        u64 size;
-       char buf[VIRTFN_ID_LEN];
        struct pci_dev *virtfn;
        struct resource *res;
        struct pci_sriov *iov = dev->sriov;
@@ -182,23 +203,14 @@ int pci_iov_add_virtfn(struct pci_dev *dev, int id)
        }
 
        pci_device_add(virtfn, virtfn->bus);
-
-       sprintf(buf, "virtfn%u", id);
-       rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
+       rc = pci_iov_sysfs_link(dev, virtfn, id);
        if (rc)
                goto failed1;
-       rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
-       if (rc)
-               goto failed2;
-
-       kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);
 
        pci_bus_add_device(virtfn);
 
        return 0;
 
-failed2:
-       sysfs_remove_link(&dev->dev.kobj, buf);
 failed1:
        pci_stop_and_remove_bus_device(virtfn);
        pci_dev_put(dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 83ce1cdf5676..e97d27ac350a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2048,6 +2048,8 @@ int pci_iov_virtfn_devfn(struct pci_dev *dev, int id);
 
 int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn);
 void pci_disable_sriov(struct pci_dev *dev);
+
+int pci_iov_sysfs_link(struct pci_dev *dev, struct pci_dev *virtfn, int id);
 int pci_iov_add_virtfn(struct pci_dev *dev, int id);
 void pci_iov_remove_virtfn(struct pci_dev *dev, int id);
 int pci_num_vf(struct pci_dev *dev);
@@ -2073,6 +2075,12 @@ static inline int pci_iov_virtfn_devfn(struct pci_dev 
*dev, int id)
 }
 static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
 { return -ENODEV; }
+
+static inline int pci_iov_sysfs_link(struct pci_dev *dev,
+               struct pci_dev *virtfn, int id)
+{
+       return -ENODEV;
+}
 static inline int pci_iov_add_virtfn(struct pci_dev *dev, int id)
 {
        return -ENOSYS;
-- 
2.17.1